WebComment: fix washing of email to admin
WebComment: fix washing of email to admin

* Some invalid markup can still be entered in comments,
  leading to possible failure of the washing of the email
  to the admin. In these cases, simply cgi.escape() the
  content.

tiborsimko/invenio,tiborsimko/invenio,inveniosoftware/invenio,inveniosoftware/invenio